Many users of modern communications own and operate multiple connected devices simultaneously. For example, it is not uncommon for mobile users to have and use, in addition to a cell phone, other devices such as laptop computers, smartphones, tablets, and personal digital assistants (PDAs). Users may also access communications using different devices at work and at home, and may travel among disparate networks with these devices. Providing access to all devices all the time can create issues.
Each communication technology exists independent of all the others, so that, for example, cell networks operate independently of cable Internet providers and vice versa. However, such technologies are not built for interoperability and have limited extensibility, and providers that wish to provide mobility for multiple devices and multi-homed devices must implement a variety of techniques in order to satisfy user needs. For example, Mobile IP does not provide a method for handling a device with multiple network interfaces (e.g. a multihoming device). As well, Mobile IP and other techniques may not work for devices that are multi-user devices, such as a shared Apple iPad, because they rely on an assumption that a single device shall be used by the same user.